An aortic dissection is a condition wherein the inner layer of the aorta tears causing the inner and outer layers of the aortic wall to separate, or dissect. Blood, under pressure, flows into the tear further separating and expanding the inner and outer aortic wall into an inflated sack known as a false lumen.
Treatment of an aortic dissection depends on the location of the dissection (ascending aorta, aortic arch, or descending aorta) and may include surgery and/or medication. Traditional open surgery inflicts significant patient trauma and discomfort, requires extensive recuperation times, and may result in life-threatening complications. Medication treatment may not be sufficient in some cases. For example, and not by way of limitation, malperfusion syndrome is a complication of aortic dissection cased by branch-vessel involvement resulting in end-organ ischaemic dysfunction. Malperfusion syndrome is one trigger for endovascular treatment. Malperfusion syndrome may be static or dynamic and result in loss of blood supply to critical organs.
To address these concerns, efforts have been made to perform aortic dissection repair using minimally invasive techniques including percutaneous transcatheter (or transluminal) delivery and implantation of a stent-graft prosthesis at a treatment site. In such methods, a stent-graft prosthesis is compacted for delivery in a catheter and then advanced, for example through the femoral artery, and through the vascular to the treatment site within the aorta. A stent-graft prosthesis is generally a stent coupled to a graft material. While stent-graft prostheses are generally considered endovascular devices, there is a developing theory encompassing a hybrid procedure wherein endovascular devices can be used in conjunction with traditional open surgical procedures.
FIGS. 1-2 illustrate an aorta 100 with an aortic dissection 102 and treatment thereof using a conventional stent-graft prosthesis 200. The aorta includes an ascending aorta 106, an aortic arch 108, and a descending aorta 110, as shown in FIG. 1. The aortic arch 108 includes a plurality of branch arteries including the innominate artery 112, the left common carotid artery 114, and the left subclavian artery 116. The descending aorta 110 includes a plurality of branch and ancillary arteries such as, but not limited to the renal arteries (not shown in FIGS. 1-3), superior mesenteric artery (SMA) (not shown in FIGS. 1-3), intercostal arteries 120 and subcostal arteries 122, providing first blood flow BF1 to bodily organs including, but not limited to the abdominal muscles, spine, intestines, kidneys, bowels, and legs (not shown in FIGS. 1-3). While FIG. 1-2 shows only intercostal artery 120 and subcostal artery 122, this is for illustrative purposes only and intercostal arteries 120 and subcostal arteries 122 each represent a plurality of arteries. In the exemplary aortic dissection 102 shown in FIG. 1, the wall of the descending aorta 110 may be injured so that a tear 124 in an inner aortic wall 126 occurs, as shown in FIG. 1. Blood, under pressure from the heart, flows into tear 124, as shown by third blood flow BF3, and splits, or dissects inner aortic wall 126 from outer aortic wall 128, forming a false lumen 130. False lumen 130 and blood therein under pressure forces inner aortic wall 126 towards a centerline CLd of descending aorta 110 such that blood flow in natural lumen 132 of descending aorta 110 is restricted/reduced. False lumen 130 and blood therein under pressure forces outer aortic wall 128 away from centerline CLd of descending aorta 110, causing a point of potential aneurysm, as shown in FIG. 1. A normal aortic wall position 134 is shown in FIG. 1 as a dotted line.
Treatment of aortic dissection 102 of aorta 100 requires that tear 124 be closed off such that false lumen 130 is isolated or depressurized. A conventional stent-graft prosthesis 200 is deployed at the site of aortic dissection 102 as shown in FIG. 2. Prosthesis 200 includes a stent frame 202, also known as a stent or stent ring, and a graft material 204. When stent-graft prosthesis 200 is deployed at aortic dissection 102 and in a radially expanded deployed configuration, a first outward radial force OF1 of stent-graft prosthesis 200 forces inner wall 126 outward, away from centerline CLd of descending aorta 110 such that inner wall 126 approaches normal aortic wall position 134, natural lumen 132 through descending aorta 110 is generally restored, and the position of prosthesis 200 is maintained with respect to tear 124 of aortic dissection 102. More specifically, when prosthesis 200 is deployed at the site of aortic dissection 102 and in the radially expanded deployed configuration, graft material 204 seals tear 124 such that blood no longer flows into false lumen 130, as shown in FIG. 2.
While tear 124 is sealed by graft material 204 of prosthesis 200 and natural lumen 132 of descending aorta 110 is restored, graft material 204 would block blood flow to any arteries emanating from the portion of the vessel bypassed by prosthesis 200. Accordingly, conventional prostheses are not placed in the descending aorta such that they would block branch arteries such as the celiac artery, the superior mesenteric artery, or the renal arteries, or accommodations must be made to maintain blood flow to these branch arteries. Further, even when located above the celiac artery, prosthesis 200 may block blood flow to some smaller arteries that provide blood flow to the spine, such as intercostal arteries 120 and subcostal arteries 122. Although not desirable, this is sometimes accepted in conventional prostheses. Further, a conventional prosthesis 200 is generally not used for a dissection in the ascending aorta 106 and aortic arch 108, as blocking blood flow to the great vessels of the aortic arch is unacceptable.
Further, the outward radial force of seal stents (at proximal and distal ends of stent-graft prosthesis 200) of conventional graft prostheses tends to create new dissections.
Accordingly, there is a need for an improved, dissection specific stent-graft prosthesis system and method to repair an aortic dissection that reduces the possibility of creating new dissections, does not restrict blood flow to branch arteries of the aorta, may be utilized within the ascending aorta and aortic arch, and has excellent flexibility for easy delivery to the treatment site.